Examples

The examples are in folders by kind (SDL2 words, see docs/SDL2.md):

The Turtle: the window shows the drawing, you type lines in the terminal (100 forward 90 right, loops allowed), then go draws at once, speed 100 and play draw stroke by stroke, list, undo, new, demo, help. Run one with lugforth examples/games/sdl2_breakout.fs, or include games/sdl2_breakout.fs from the examples folder. On the bare-metal boards the folders are kept on the disk or the stick (include games/sdl2_snake.fs, include system/varvara/varvara_rpi.fs), and the website (ports/web/BUILD) copies the files that run in the browser by name.

In the browser

Several examples also run in the browser, from the website, with the very same files:

• Terminal: the Forth prompt, also on a phone. Type sdl2, then 10 10 150 140 line, red color 200 20 100 60 box, s" t200 o4 c d e f g" play. terminal.html?run=sdl2_roguelike.fs runs a game file of the demo before the prompt.
• Games: Breakout, roguelike, raycaster (the 3D maze, steered with the mouse), pinball.
• Music: drums, FM synthesizer (with MIDI input).
• Drawing from HTML (web/): a button calling a Forth word, string art, vector lettering and its outline.

Benchmarks: lugforth vs C vs uxn

Two benchmarks, each in three files doing the same work (same algorithm, constants and data): bench_sieve and bench_lines, as .fs, .c and .tal (uxn assembly). make bench builds and runs all six; make help lists the targets. The ratios matter, the times depend on the machine.

Pure interpretation is about 100 times slower than C for tight integer loops, for lugforth and uxn alike. With real work behind a library or device call (the SDL2 renderer, uxn's Screen) the gap shrinks to 7-9 times, which is the case that matters for drawing games.

bench_lines.fs stays open on the last frame (Esc to quit); BENCH_HEADLESS=1 exits at once. make view-lines, view-lines-c and view-lines-uxn open a window to check the drawing by eye.

pinball/

lugforth examples/games/pinball/pinball.fs: a menu (up/down, Enter, or 1 and 2; Esc in a game comes back to it) with two tables. common.fs holds what they share (fixed point helpers, 3x5 font, seven segment digits).

• raid.fs, Night Raid: lines on a black screen, the score on a panel, missions from cadet to ace, gravity, bounce and number of balls to choose, and a demo where the machine plays until Enter. Keys: z/m (or the shifts, or the arrows) for the flippers, down held then let go for the plunger, space or n to nudge (TILT if too much).
• night.fs, Night Strike: a table laid out after an early 80s coin-op pinball whose screen captures and fix mode (38 game variables) were studied: NIGHT lanes, DROP targets, A B C D, F L Y, a captive hole, a dive bomb chute that can hold balls (multi-ball), two spinners, bonus and multipliers, 1 to 4 players, coins (q) and start (s or Enter), free games, tilt (a and l nudge). The rules are in the header of the file. The physics is in fixed point (4096 units to a pixel, 6 steps a frame): circle against segments, turning flippers that give their speed to the ball, bumpers and slingshots that kick it. It also runs in the browser, ports/web/sdl2_pinball.html (written blind, not run here), with touch buttons for the Raid keys. Its arithmetic stays within 32-bit cells, which the web build has. play_raid.fs and play_night.fs start one table without the menu (used by make smoke).

varvara/

A Uxn/Varvara virtual machine in Forth: lugforth examples/system/varvara/uxncli.fs program.rom runs a ROM in the terminal. See varvara/README.md.

txt2tags.fs

A converter from basic txt2tags syntax to HTML, written in Forth:

lugforth examples/utils/txt2tags.fs examples/utils/txt2tags_demo.t2t > demo.html

or include examples/utils/txt2tags.fs then s" doc.t2t" t2t-file. The header comment lists the supported syntax.

Games after r3forth

r3forth by Pablo Reda (MIT license) is a Forth of the ColorForth family with its own syntax (:word, #var, conditionals followed by ( ) blocks, fixed point numbers), so its games are not loaded as they are but written again in lugforth, keeping their ideas. Only libSDL2 is needed: no font or image files, the digits come from a 3x5 bitmap. They also run on the bare-metal boards (ports/rpi, ports/efi: include sdl2_tetris.fs from the card or the stick).

• sdl2_tetris.fs: the seven pieces, wall kicks, a ghost piece, the next piece, levels; r3's score table (40, 100, 300, 1200 times the level). Left/right, up or x turns, down drops faster, space drops at once, p pauses, r after the end.
• sdl2_snake.fs: through the edges as in r3, one more cell for each fruit and a little faster, and the end when it bites itself (r3's has none). Arrows or wasd, p, r after the end.
• sdl2_minesweeper.fs: r3's three levels (1, 2, 3: 9x9 and 10 mines, 16x16 and 40, 30x16 and 99) and its list rather than recursion to open the empty cells; the first cell is never a mine, a click on a number opens around it when its flags are all there. Mouse (left opens, right flags) or keyboard (arrows, space opens, f flags), so it plays on the PC under UEFI where the mouse may be missing.

Beside them, written for lugforth:

• sdl2_raycaster.fs: a walk in a maze drawn by raycasting (one ray per screen column, 16.16 fixed point, no floats), after the raycasting demo of JS-Forth (Chris Curl, MIT, in NOTICE). The mouse turns (the further from the middle of the window, the faster) and looks up or down; w a s d (or z q s d on an AZERTY keyboard, by key place) and the arrows walk and turn; m switches the mouse off. A map of the maze, with you in red, is at the top left. Checked by screenshots under Xvfb with xdotool (keys and mouse), and in headless Chromium for the web page (ports/web/sdl2_raycaster.html: it draws, a key moves the view; mouse turning not confirmed there). The math is 32-bit safe (products through */) because the browser has 32-bit cells. The boards have not run it (on them scan? is 0, so w/s/a/d by letter only, and the mouse is not tried).
• sdl2_mastermind.fs: find the four hidden colors (out of six, repeats allowed) in ten tries; after each row, a black peg per color at its place, a white one per right color elsewhere. Keys 1 to 6 put a color in the frame, left/right move it, up/down change its color, backspace takes it away, space or enter checks the row; or the mouse (a color below, a hole, the green box). r a new game.

games_tests.fs tests the logic of the four without opening a window (make test-ports).

Ports from eForth Windows

eForth Windows by Marc Petremann is a ueForth for Windows, so its code loads in lugforth almost as is (value/to, { } locals, vocabulary, :noname, floating point). Three of its projects are here; they are GPL (derived from his code), unlike the rest of the repository. Each file says what is his and what is new.

• 2048.fs: the game in a terminal (include examples/games/2048.fs, then 2048-play; arrows or wasd). sdl2_2048.fs is the same game in an SDL2 window (lugforth examples/games/sdl2_2048.fs; arrows, wasd or a mouse drag, r restarts; the tiles slide and pop, --no-anim after the file name turns that off), digits drawn from a bitmap so no font is needed. The original only has the grid and its display; moves, merging, score, keys and end are new.
• 3d.fs + sdl2_3d.fs: 3D wireframes (lugforth examples/graphics/sdl2_3d.fs). 3d.fs has the points, edges, sine table, rotation and perspective (no display); the original draws with the Windows GDI, here SDL2.
• inference/ (inference.fs, weather.fs, lamp_diagnosis.fs) (explanations in inference/README.md, in French in inference/README.fr.md): facts (FACT:), rules (:CONDITION, :ACTION, RULE:) and the engine loop infer (new): include examples/utils/inference/inference.fs, include examples/utils/inference/weather.fs, also facts -1 to rain -1 to cold infer .facts.

make test-ports runs 2048_tests.fs, 3d_tests.fs, inference/inference_tests.fs, inference/lamp_diagnosis_tests.fs and games_tests.fs.